ABSTRACT Core C Core C has both research and service goals, with the overall theme of developing new and useful imaging and dosimetry approaches to help optimize PDT, both for experimental protocols as well as clinical trials. The systems used by each project vary considerably, yet the file systems, data analysis, planning and dosimetry concepts can be centralized and inter-project communication in this area can significantly enhance the quality of research. The core is subdivided into four distinct aims, including (i) developing clinically viable tools for structural and functional imaging as well as dosimetry; (ii) providing baseline data for tumor models and imaging in vivo; (iii) methods for quantitative molecular imaging in vivo; and (iv) technology and methodology translation and adoption. These aims all work with the projects to ensure that developments from one project may assist in another, and that methods, doses, image files, and developed software gets used to the highest potential. The core will assist Projects 1 and 2 in establishing truly useful dosimetry tools customized for the clinical trials. The variance of PS concentration will be studied in both skin and pancreatic cancer models. Quantification of key receptor changes in vivo will be developed. Specialized instrumentation and expertise exists across all four centers, with a large locus of tools and equipment in the MGH & Dartmouth sites, and this will be coordinated, scheduled and training provided through quarterly planned organizational meetings. Technical experts exist at each center though, and these frequent meetings coordinated by the core help to ensure that expertise and resources are utlized to maximum benfit. Travel between sites is planned judiciously to maximize cost/benefit, especially when training or prototyping measurements or trials, and internet conferences are utilized frequently. The complexity of technologies used is high, and sharing expertise about these significantly benefits the overall program participants. The complex issue of technology transfer is incorporated, as we have mulitiple partners in companies, as well as experienced technology transfer offices of each institution, and the CIMIT center at MGH. Coordination of this with high level planning meetings is central to ensuring that technologies and methodologies are translated into the program or out of the program into industry use. RELEVANCE TO PUBLIC HEALTH Core C provides the medical imaging, dosimetry, technology transfer expertise that is needed for the projects to be maximally successful. Since PDT is a technology-based intervention which requires imaging and analysis of therapeutic outcome, the core will help lead our efforts in excellence within this area. Superior treatment outcomes in the pancreas and skin cancer clinical trials will be a result